1. Field of the Art
This invention relates to an IC package transfer and relocation mechanism particularly suitable for use on an IC package fabrication line or on an IC package inspection line for the purpose of transferring and relocating a large number of IC device packages between different types of IC holder trays.
2. Prior Art
There are a great variety of molded packages of IC devices (hereinafter referred to as "IC devices" or "IC packages" for brevity), which can be classified, for example, into a pin insertion type and a flat mount type according to the shape of lead pins which are led out of a molded package body. In the case of the pin insertion type IC packages, the lead pins which are led out on the opposite lateral sides of a package body are bent downward for insertion into through holes provided on a circuit board. In handling IC packages of this type, it is the general practice to use magazines which are adapted to accommodate a plural number of IC packages in a row within a tubular housing.
On the other hand, in the case of the flat mount type IC packages including SOP (Small Outline Package) and QFP (Quad Flat Package), the lead pins which are led out on the opposite two sides or on the four sides of a package body are once bent downward in middle portions and then bent again in lateral directions at a level slightly lower than the bottom surface of the package body. In some cases, the lead pins which are led out on the two or four sides of a package body are turned inward toward the bottom side of the package as with SOJ (Small Outlined J-bend Package) or PLCC (Plastic Leaded Chip Carrier). These flat mount type IC packages are designed to be mounted in position on a circuit board by soldering, and are recently used increasingly as devices which can contribute to reductions in thickness and size of circuit boards.
In contrast to the pin insertion type IC packages which can be accommodated in a cylindrical magazine, it has been the general practice to use flat trays as a jig in transferring flat mount type devices. The trays of this sort are usually in the form of a rectangular flat plate which is formed with a large number of recessed IC holder nests in an array with predetermined spacings between adjacent IC holder nests. Each IC holder nest is formed in a depth which is greater than the height of a nesting IC device from its lead pins to the top side of its package body, so that a number of loaded trays can be conveniently stacked one on another when in storage or at the time of transportation. The respective holder nests on a tray are open on the upper side, permitting easy access to IC devices by a handling means such as a suction or vacuum gripper or the like.
In a stage of quality control prior to shipment, it is usually the case that manufactured IC device packages are tested by measurements of electrical characteristics. The test of this nature is conducted on an IC tester which is provided with a number of contacts to be connected to the lead pins of IC devices. In order to carry out this inspectional test efficiently, a plural number of similar IC packages are tested simultaneously on an IC tester by the use of a tester tray which is arranged to hold a plural number of IC devices in predetermined arrayed positions, more particularly, by bringing a large number of sets of contacts on a tester head into engagement with lead pins of the respective IC packages which are held in predetermined positions on the tester tray relative to the tester head.
Generally, trays which are used for the purpose of storage or transportation of IC packages, (hereinafter referred to simply as "storage tray" for brevity), are arranged to hold as many IC packages as possible in a relatively highly packed state. In contrast, the tester trays are required to hold IC packages in relatively widely spaced positions because of the need for providing spaces, on the part of tester trays, for clamp mechanisms which hold the respective IC packages accurately in position on the tester trays, along with alignment mechanisms for bringing the tester contacts and lead pins into alignment with each other.
Therefore, prior to a product test, a storage tray which holds a plural number of IC packages is placed on a loader to transfer the respective IC packages onto a tester tray, and, after finishing a test, the tested IC packages are unloaded from the tester tray and placed again on a storage tray in classified sections, i.e., either in a acceptable section or a defective quality section, according to test results. For this purpose, a robot machine with a suction gripper is provided at the testing station to eject tested IC device packages from a tester tray and transfer and relocate the same onto a storage tray accordingly.
The storage and tester trays are provided with recessed IC package holder nests in arrays of different pitches or with different spacings for the reasons as explained above, necessitating to transfer and relocate the tested IC devices one by one from a storage tray to a tester tray despite low IC transfer speed and efficiency. In some cases, these problems arising from the difference in pitch of arrayed IC package holder nests between the two types of trays are coped with by using a pair of suction grippers which are movable toward and away from each other in such a way as to compensate for the difference in pitch of arrayed IC package holder nests on the two trays. Namely, at the time of transferring IC packages to or from a storage tray, the interval between the two suction grippers is narrowed into conformity with the pitch of an array of IC holder nests on the storage tray, and, at the time of transferring IC packages to or from a tester tray, the interval between the two suction grippers is broadened into conformity with the pitch of an array of IC holder nests on the tester tray.
Recently, reductions of testing time have been achieved to some extent by introduction of IC testers of higher performance quality. Nonetheless, higher efficiency and speeding of inspections by IC testers cannot be attained without an IC transfer and relocation mechanism which is capable of transferring IC device packages between a storage tray and a tester tray efficiently in shortened time periods. Therefore, an improvement in transfer speed of IC packages has a great importance from the standpoint of enhancing efficiency and speeding the inspections by IC testers.